Flexible linkage wheel supported rotatable drum

ABSTRACT

A horizontally positioned rotatable cylindrical drum cradled in a pair of spaced-apart chains suspending said drum, and a plurality of wheels rotatably mounted on spaced-apart axles supported by each chain, said wheels rotatably supporting the drum. The rotating drum can be used to debark logs and mix and stir materials being treated.

United States Patent [191 OBrien et al.

[451 Feb. 4, 1975 FLEXIBLE LINKAGE WHEEL SUPPORTED ROTATABLE DRUM [75]Inventors: Richard Edward OBrien, Geneva;

Arthur Raymond Simpson, Riverside, both of 111.

[73] Assignee: Chicago Bridge & Iron Company, Oak Brook, 11].

22 Filed: Mar. 26, 1973 21 Appl. No.: 344,531

[52] U.S. Cl 259/89, 241/178, 248/130, 308/203 [51] Int. Cl B0lf 9/02[58] Field of Search 259/89, 90; 248/130; 241/178; 68/140; 51/164;308/203, 204;

[56] References Cited UNITED STATES PATENTS 694,565 3/1902 Mason, Jr.259/89 2,290,565 7/1942 Lagana 2,494,110 1/1950 Stiller 214/3962,707,339 5/1955 Berge 259/90 X 2,793,920 5/1957 Haaff 308/204 3,216,66611/1965 Svensson et a1. 259/89 X 3,507,469 4/1970 Vanderheyden 248/223,509,742 5/1970 Bauer 248/22 X 3,744,837 7/1973 Foster 294/74 FOREIGNPATENTS OR APPLICATIONS 769,894 6/1934 France 308/203 PrimaryExaminerHarvey C. Hornsby Assistant Examiner-Alan Cantor Attorney,Agent, or Firm-Merriam, Marshall, Shapiro & Klose [57] ABSTRACT Ahorizontally positioned rotatable cylindrical drum cradled in a pair ofspaced-apart chains suspending said drum, and a plurality of wheelsrotatably mounted on spaced-apart axles supported by each chain, saidwheels rotatably supporting the drum. The rotating drum can be used todebark logs and mix and stir materials being treated.

21 Claims, 20 Drawing Figures PATENTED 41% 3,863,902

SHEET 30F a PATENTED FEB 4191s SHEET 0F 8 NV QM RQN Qw WW I mum AWN QQNMu QNN PATENTED 4|975 3,863,902

SHEET 8 OF 8 PATENTED FEB 41975 SHEET 7 OF 8 PATENTEU 4|975 3.863802SHEET 80F 8 FLEXIBLE LINKAGE WHEEL SUPPORTED ROTATABLE DRUM Thisinvention relates to industrial processing apparatus which employs asubstantially horizontally positioned rotating drum. More particularly,this invention is concerned with improvements in such apparatus in whichthe drum rotates on wheels suspended by nontraveling chains.

Many industrial processes employ a rotating horizontal metal drum forprocessing heavy solid materials. The drum is usually rotatablysupported in one of two ways. One way is to suspend the drum in a pairof spaced-apart endless chains. The endless chains run or travel on barrings mounted on the drum at the same speed as the rotating drum. Such asystem is disclosed in US. Pat. No. 3,269,438. Traveling chain supporteddrum apparatus withstands high impact loads and shock applied to thedrum, very satisfactorily. The second usual way to support the drum ison trunnion wheels. See US. Pat. Nos. 3,262,477 3,701,487 and 3,709,268.

According to the present invention there is provided novel apparatuscomprising a horizontally postioned rotatable cylindrical drum rotatablysupported on wheels mounted on at least a pair of spaced-apartnontraveling chains suspending said drum in cradled arrangement with thechains in tension. Each chain has a plurality of wheels rotatablymounted on spacedapart axles supported by the chain. The wheels on eachchain are placed in direct rolling contact with the drum surface itselfor they are placed in contact with a track placed around the drum. Thewheels are adapted to support the drum and rotate it in a directioncounter to rotation of the wheels.

The chain used in the apparatus of this invention can be made of linksand the ends of the links can be connected together by an axle. At leastsome of the wheels can be mounted on such axles. Alternatively, the endsof adjoining links can be connected together by a pivot pin and at leastsome of the wheels can be mounted on axles supported by the linksbetween adjacent pivot pms.

An important feature of the subject invention is the use of chains whichhave two ends as distinguished from endless chains. Each chain inaddition is nontraveling and has its ends connected to support meanswhich is stationary or disp;aceable through a limited distance. Thechain and wheels are unrestrained or unsupported apart from the drum andsaid support means. Neither the chain links nor the wheels have back-upsupports to hold them in place. The chain is free to move lateral to thedrum longitudinal horizontal axis. Ths support means can be providedwith means for adjusting the effective length of the chain to therebyraise and lower the drum, or it can be provided with resilient means forabsorbing tensile forces applied to the chains. The resilient means canbe a spring or polymeric material like rubber or its equivalent. Fluidpressure means can be included as part of the chain support means forabsorbing tensile forces applied to the chains. The fluid pressure meanscan constitute pneumatic or hydraulic means.

One, two or more wheels can be mounted on the same axle on the chain andsome or all of the wheels on an axle can be mounted between or outsideof adjacent link plates or elements.

The track means against which the wheels ride can constitute a singlemetal ring or a pair of metal rings mounted on the drum. The type oftrack to be used should be selected with due regard to the size andweight of the drum and the load to be placed therein, the number andsize of the wheels to be used and whether the wheels will be flat rimmedor flange rimmed.

The invention will be described further in conjunction with the attacheddrawings in which:

FIG. I is a side elevational view of apparatus having a drum rotatablysupported on wheels mounted on a pair of two-ended nontraveling chains;

FIG. 2 is a front elevational view of the apparatus of FIG. 1 takenalong the line 2-2;

FIG. 3 is a partial sectional view of the apparatus of FIG. 1 takenalong the line 3-3;

FIG. 4 is a plan view of apparatus essentially like that shown in F165.1 and 2 but with hydraulic means supporting the chain ends;

FIG. 5 is a side elevational, partly schematic, view showing the drum ofapparatus similar to that in FIG. I in tilted position;

FIG. 6 is an elevational view of the chain with wheels used to rotatablysupport the drum of FIGS. 1, 2 and FIG. 7 is a sectional view takenalong the line of 77 of FIG. 6;

FIG. 8 is a sectional view through a two ring track with a two flangedwheel on each ring;

FIG. 9 is a sectional view through a single ring track showing twosingle flanged wheels on the same ring;

FIG 10 is a sectional view of a single ring track showing a single wheelwith a flange on each edge of the rim;

FIG. 11 is a sectional view of a drum and single ring in which separatedwheels ride on the drum surface with the ring provided as a wheel guide;

FIG. 12 is a sectional view of a single ring track having a centralgroove for a single wheel taken along the line12-I2 of FIG. 13;

FIG. 13 is a paln view of part of a chain showing a wheel mounted on anaxle which also joins the ends of adjacent links together;

FIG. 14 is a plan view of part of a chain showing a wheel mounted on anaxle between opposite link plates and between the ends of the link;

FIG. 15 is an elevational view, partially in section, of a coil springsupport for the end of a chain;

FIG. 16 is an elevational view, partially in section, of a fluid supportfor the end of a chain;

FIG. 17 is a schematic end elevational view of a chain having supportingwheels for the drum mounted close together;

FIG. 18 is a view similar to FIG. 17 but with the wheels spaced fartherapart;

FIG. 19 is a schematic end elevational view of a chain having supportingwheels for the drum mounted close together and with wheels located up tothe drum equator to facilitate having the chain ends hang verticallyfrom supporting beam and not contact the drum; and

FIG. 20 is a schematic end elevational view of a chain having wheels ofprogresively larger size from the upper part to the bottom part of theU-shaped suspended chain.

So far as is practical the same elements or parts which appear in thevarious drawings will be identified by the same numbers.

As shown in FIGS. 1 to 3, longitudinal horizontal structural beams and16 are joined to the pair of lateral horizontal beams 17 and 18, all ofwhich comprises a base 10 which is secured to foundation 21. The base 10serves to support one end of the drum 70. The other end of the drum issupported by a base 10A which is secured to foundation 21A. Base 10Aconsists of the same elements as base 10 so the elements have been giventhe same numbers. Two support means 25 and are mounted on base 10 andthe two support means 45 and 55 are mounted on the base 10A. The supportmeans 35 has a pair of spaced-apart upright beams 36 and 37 which aretilted outwardly from drum 70 as shown in FIGS. 2 and 3. Beam 38 isjoined to the top of beams 36 and 37. Braces 39 and 40 serve to supportthe beams 36 and 37 against tilting longitudinally. Each of the beams 36and 37 is outwardly braced by web and flange weldments 41 and 42, and isinwardly braced by web and flange weldments 43 and 44 (FIG. 2). Theother support means 25, 45 and are constructed in the same way assupport means 35 so that the same parts are identifled by the samenumbers in each support means in the drawings.

Drum 70 is suspended between support means 25, 35, 45 and 55 by means oftwo spaced-apart identical chains and 61. Chain 60 is joined at one endto rod 62 which extends through beam 38 and through coil spring 63.Retaining nut 64 holds rod 62 in place and thereby places spring 63 incompression. See FIG. 15. The other end of chain 60 is joined to rod 65which extends through beam 38 and spring 66. Rod 65 is secured in placeby nut 67, thus placing spring 66 in compression. Chain 61 is supportedin the same way as chain 60 so the same parts are indentified with thesame numbers.

Chain 60 (FIGS. 1, 2 and 6 is composed of a link 80, comprising a singlelink plate, and alternating links 81. Each link 81 is composed of twolink plates 82 and 83. Axle 84 passes through the end of link and theends of link plates 82 and 83 and joins them together. Each axle 84supports a pair of wheels 85, 86; 85A, 86A; 85B, 86B mounted outside ofthe links. Wheels 85 and 86 are spaced closertogether than wheels 85Aand 86A as shown in FIGS. 6, and wheels 85A and 86A are spaced closertogether than wheels 85B and 86B. The increased spacing between thewheels permits tilting of the drum by raising or lowering one end of thedrum without having the chain bent or having the wheels jump the trackon which they roll.

As shown in FIG. 1, each spaced-apart track 90 and 90A is identicalalthough they could be different with different shaped wheels on eachchain. Track 90 is a single circular ring'mounted tightly on the outsideof drum 70. Track 90 has a raised middle surface 91 and stepped-downside surfaces 92 and 93. Wheels 85, 85A and 85B roll on surface 92 andwheels 86, 86A and 86B ride on surface 93. The ring surfaces 92 and 93are made wide enough to adequately support the wheels even when the drumis tilted.

The increased distance between wheels 85B and 86B, and 85A and 86A,prevents the wheels from binding against the edge or side of raisedcentral or middle surface 91. The dotted lines shown in FIG. 6 representthe position of track 90 when the drum is tilted, such as shown in FIG.5, and the chain 60 is maintained vertical. The increased clearancebetween the wheels located towards the equator of the drum permits thetilting without putting a damaging strainon the wheels or the chain. Ofcourse, if it is not desired to tilt the drum then the space between thewheels can be maintained uniform.

Rotation of drum 70 can be achieved by means of chain 95 which runs onring sprocket 96 mounted circumferentially on the drum. Chain 95 isdriven by sprocket 97 mounted on shaft 98 in operative connection withmotor 99 through gear reducer 100. Sprocket 101 (Fig. 3) serves tocontrol tension on chain 95. While one means of rotating drum 70 hasbeen described, it is to be understood that other suitable means canalso be used.

Replacement of the chains supporting drum 70 as shown in FIG. 2 can bereadily achieved by releasing nuts 64 and 67 and lowering the drum intocontact with the top of members 43 in which the drum will rest incradled position. The chains can then be completely removed and replacedor any of the wheels can be removed and be repaired or be replacedwithout dismantling the links.

The supporting means of FIGS. 1 and 2 permits ready removal of the drum70 by lifting since there is no overhead obstruction.

With reference to Figure 4 it will be seen that the chain 60 issupported at both its ends, and that chain 61 is supported at one end,(although it could be supported at both ends) by fluid pressure means.Hydraulic cylinder 105 is placed in supporting communication with oneend of chain 60 and hydraulic cylinder 106 is placed in supportingcommunication with the other end of chain 60. Hydraulic line 107 extendsfrom pump 108 to cylinder 106 shown in greater detail in FIG. 16.Hydraulic line 109 extends from line 107 to valve 110 and line 111extends from valve 110 to cylinder 105. Line 112 extends from pump 108to valve 113 and line 114 extends from valve 113 to a hydraulic cylinder115 in communication with one end of chain 61. With valve 110 closedcylinders 106 and 115 can be activated to raise and lower both ends ofthe drum at a uniform rate. However, to tilt the drum, such as to theposition shown in FIG. 5 to facilitate emptying the contents therefrom,valve 113 can be closed and valve 110 can be opened to activate bothhydraulic cylinders 105 and 106 to raise or lower that end of the drum.Although perhaps only one of the cylinders 105 and 106 need be activatedto tilt the drum it is usually advisable to activate both of them tokeep the wheels positioned symmetrically below the drum.

Tilting of drum 70 will generally necessitate the use of means tomaintain the drum in a relatively fixed position relative to thesupporting chains so that the drum does not become undesirably displacedlongitudinally toward the low end of the tilted drum. To keep the drumin position and still permit it to rotate a suitable thrust means can beemployed. One such system is shown in FIG. 5. Thrust ring is mounted todrum 70. Thrust wheels 121 and 122 are mounted on axles supported inblock 123. Each of the wheels rotatably presses against one side ofthrust ring 120 to keep the drum in relatively fixed longitudinalposition.

FIGS. 8 to 14 and 17 to 20 illustrate additional chain, track and wheelarrangements which can be used in the invention although it should beunderstood that the invention is not to be limited to the specificallyillustrated embodiments of the invention.

In FIG. 8, a pair of spaced-apart rings 125 and 126 are welded to drumand together constitute a track. Wheels 127 and 128, mounted on the sameaxle on a drum supporting chain, roll on rings and 126. Each of thewheels has a flange on each of its rim edges to keep the wheel on thering.

FIG. 9 shows a track comprised of a flat ring 130 mounted on drum 70. Apair of wheels 131 and 132 is mounted on an axle supported by a chain.Each wheel has a flange on its outer rim edge. The flanges prevent thewheels from being moved laterally with respect to ring 130 duringrotation of the drum.

FIG. 10 illustrates a track having a single flat ring 135 mounted ondrum 70. A double-flanged wheel 136 supported by an axle in a chainrides on the ring. The flanges keep the wheel from moving off of thering during rotation of the drum.

Another arrangement is shown in FIG. 11. Ring 138 is mounted on drum 70.However, the wheels 85 and 86 run on the surface of drum 70 on each sideof ring 138. Such an arrangement would not generally be use ful unlessthe drum surface was substantially smooth and free of troughs orcorrugations. Even then it would not be used under normal circumstanceswhere the drum was of large size and the load carried by the drum wasrelatively large.

FIGS. 12 and 13 show a further embodiment of chain, wheel and trackapparatus which can be used. Chain 140 has alternating links 141 and142. Each link 141 has a pair of link plates 143 which are joined attheir ends to an axle 144 on which wheel 145 is mounted between the linkplates. Each link 142 has a pair of link plates 146 which are joined attheir ends to axle 144. As shown in FIG. 12, drum 70 has a grooved ring147 mounted thereon. Wheel 145 is adapted to roll in the groove in ring147 and thereby lateral movement of the wheel with respect to the ringis prevented.

Still another chain-wheel arrangement is shown in FIG. 14. The chain iscomposed of alternating links 150 and 151. Link 150 has a pair of spacedapart link plates 152 joined at each end to a pivot pin 153. Link 151 iscomposed of a pair of link plates 154 joined at their ends to pivot pins153. Axle 155 is supported by the pair of link plates 154 between theends of link 151. Wheel 156 is mounted on axle 155 and is adapted toroll in ring 147 as shown in FIG. 12. Of course, wheel 156 can be shapeddifferently as for example it can have one or two flanges as shown onthe wheels in FIGS. 8 to 10.

It is considered more satisfactory to mount the wheels outside of thechain links as shown in FIGS. 7 and 9, than inside of the links as shownin FIGS. 13 and 14 for ease of installation and removal during repairoperation since the links themselves need not necessarily bedisassembled to remove the wheels.

The spacing of the wheels on the chain, and the size of the wheels, areto be determined in light of the size of the drum and its intended use.FIGS. 17 to 20 show some arrangements and positioning of the wheelswhich can be used.

The supporting arrangement of FIG. 17 employs seven single wheels, orseven dual wheels in side-byside relationship, as the main supportingstructure for the drum 70. Side wheels 161 are positioned higher up thechain and serve to keep the chain links from rubbing against the drum.

The wheels 165 are positioned equidistant from each other on the chainshown in FIG. 18 to support drum 70.

FIG. 19 discloses drum 70 supported by a chain having a series of elevenwheels 166 equally spaced on a chain and with wheels 167 positionedabout at the equator of the drum. The ends 168 and 169 of the chain areconnected to supporting beam 170.

The supporting system shown in FIG. 20 could be used for heavy drumswhich handle heavy loads. The supporting system of FIG. 20 has beendesigned to have the lower central wheel 171 the largest with theadjoining wheels 172 slightly smaller. Wheels 173 are smaller thanwheels 172, and wheels 174 are smaller than wheels 173.

All of the drum supporting systems described herein are operable withouthaving the chain links rub against the drum or the wheel tracks on thedrum.

Although a minimum of two spaced-apart U-shaped chain loops are used tosupport a drum, additional chain loops can be used to support a longdrum, even a drum which is not dimensionally precise longitudinally orin circularity since the chains and supporting means for the chainsprovides a self-adjusting feature that achieves dimensionalaccommodation of the drum automatically, particularly when at least oneend of each chain loop is supported by springs or a hydraulic supportmeans which equalizes the load on each chain as the drum rotates.

The wheels are generally positioned on the chains so that the axis ofthe drum is parallel to the axes of the wheels. This avoids unduefriction between the rotating drum and the wheels. However, it issometimes advisable to position the drum so that its axis isnon-parallel to the axes of the wheels, such as when it is desirable totilt the drum to a position, such as shown in FIG. 5, to effect fastdischarge of material from the drum. Fast empyting of logs debarked inthe drum is desired in some pulp mills which switch from soft wood logsto hard wood logs during operation of the plant.

The axles or pins joining the chain links together, and the mounting ofthe wheel axles in the chain links, can be provided with enoughclearance or play to permit automatic accommodation to any dimensionalvariations which may exist between the wheels and the drum, includingvariations between the mating faces of the wheels and tracks on thedrum. In making such accommodations the wheel axes can vary from theirnormal position parallel to the drum axis.

The drum and wheel tracks are generally made of metal, and advisably aremade of steel. The wheels are also advisably made of metal andpreferably steel. However, other materials can be used for the drum,tracks and wheels if desired.

Apparatus provided by this invention is particularly useful in removingbark from logs to prepare them for conversion to pulp. For this reasonlogs are shown tumbling in the drum in FIG. 2. The rotating drum canalso be used to mix and stir materials.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. Apparatus comprising:

a horizontally positioned rotatable cylindrical drum;

a pair of spaced-apart circular track means mounted circumferentially onthe drum;

a pair of spaced-apart nontraveling chains suspending said drum incradled arrangement with the chains in tension;

each chain having two ends, with the ends of each chain connected to asupport means;

a plurality of wheels rotatably mounted on spacedapart axles supportedby each chain, said wheels rotatably contacting one of the track meansand thereby rotatably supporting the drum;

the axis of the drum being substantially parallel to the axes of thewheels;

said chain and wheels being unrestrained apart form the drum and saidsupport means and;

power drive means connected to said drum to rotate said drum while beingcradled between said chains.

2. Apparatus according to claim 1 in which at least some of the supportmeans include means for adjusting the effective length of the chainwhich it supports.

3. Apparatus according to claim 1 in which at least some of the supportmeans include resilient means for absorbing tensile forces applied tothe chains.

4. Apparatus according to claim 3 in which the resilient means isrubber.

5. Apparatus according to claim 1 in which at least some of the supportmeans include fluid pressure means for absorbing tensile forces appliedto the chains.

6. Apparatus according to claim 5 in which the fluid pressure means is apneumatic means.

7. Apparatus according to claim 5 in which the fluid pressure means is ahydraulic means.

8. Apparatus according to claim 1 in which each chain is made of links,the ends of adjoining links are connected together by an axle, and atleast some of the wheels are mounted on such axles, said wheels beingadapted so that the drum is rotatably supported by the wheels contactingthe track means to rotate in a direction counter to rotation of thewheels.

9. Apparatus according to claim 8 in which a substantial number of axlessupport two wheels and the ends of the links joined to an axle arejoined thereto between the two wheels.

10. Apparatus according to claim 9 in which the two wheels on the sameaxle are positioned to ride on one of the track means mounted on thedrum.

11. apparatus according to claim 10 in which the track means is a singlemetal ring mounted on the drum.

12. Apparatus according to claim 10 in which the track means is a pairof metal rings mounted on the drum.

13. Apparatus according to claim 8 in which some links comprise a pairof link plates and a number of such links have the axle mounted wheelsbetween the link plates.

14. Apparatus according to claim 1 in which each track means is a singlemetal ring mounted on the drum.

15. Apparatus according to claim 1 in which each track means is a pairof metal rings mounted on the drum.

16. Apparatus comprising:

a pair of chain with each chain having two ends;

the two ends of each chain being connected to support means to form asubstantially U-shaped loop and with each loop being spaced from theother loop;

at least one end of one chain being adjustable with respect to thesupport means to vary the height of the U-shaped chain loop;

each chain having a plurality of wheels rotatably mounted onspaced-apart axles supported by each chain;

an essentially horizontally positioned rotatable cylindrical drumcradled in the U-shaped chain loops, with the chains in tension;

a paii'of spaced-apart circular track means mounted circumferentially onlthe drum with the wheels of each chain being in drum supportingrotatable contact with a track means;

said chain and wheels being unrestrained except by the drum and saidsupport means; and

power drive means to rotate the drum while being cradled between saidchains.

17. Apparatus according to claim. 16 in which the axis of the drum isparallel to the axes of the wheels.

18. Apparatus according to claim 16 in which the axes of the wheels arenonparallel to the drum axis.

19. Apparatus according to claim 16 in which the chain is made of linksand the links are maintained out of contact with the drum.

20. Apparatus according to claim 16 in which the chains are made oflinks and the links are joined together with sufficient clearance topermit accommodation of dimensional variations between the wheels andthe drum.

21. Apparatus comprising:

a horizontally positioned rotatable cylindrical drum;

a pair of spaced-apart circular track means mounted circumferentially onthe drum;

a pair of spaced-apart nontraveling chains connected to a support meanssuspending the chains in slinglike contour with said drum suspended bythe chains in cradled arrangement with the chains in tension;

a plurality of wheels rotatably mounted on spacedapart axles supportedby each chain, said wheels rotatably contacting one track means andthereby rotatably supporting the drum;

the axis of the drum being substantially parallel to the axes of thewheels;

said chain and wheels being unrestrained except by the drum and saidsupport means; and

power drive means connected to said drum to rotate said drum while beingcradled between said chains.

22 35 UNITED sures PATENT OFFICE "1 I I i CERTEFELATE G1 CORRECHONPatent No. 863r902 Dated ry 4 1975 Inventm-(s) Richard OBrien et al.

It is certified that error appears in the above-identified patent .andthat said Letters Patent are hereby corrected as shown below:

' Column 1, line 2% after 3,262,477" insert a comma lg' ne 24-, cmcfpostioned" to --positioned-; line 48, change "disp;aceable" to---displaceable-; line 54, change "Ths" to -The--; column 2, line 41,change "paln" to plan--; l ine 6 Cl, after "from" insert -a-; column 7,line 15, change "means and;" to means; and--; line 48, change"a'qaparatus to --Apparatus---; column 8, line 2? change "lthe" to--the; line 51, after "one" insert -of the--.

Signed and sealed this 15th day of April 1975.

Art-resting Q'fic r and Trademarks L. Page 1 of 1 J

1. Apparatus comprising: a horizontally positioned rotatable cylindricaldrum; a pair of spaced-apart circular track means mountedcircumferentially on the drum; a pair of spaced-apart nontravelingchains suspending said drum in cradled arrangement with the chains intension; each chain having two ends, with the ends of each chainconnected to a support means; a plurality of wheels rotatably mounted onspaced-apart axles supported by each chain, said wheels rotatablycontacting one of the track means and thereby rotatably supporting thedrum; the axis of the drum being substantially parallel to the axes ofthe wheels; said chain and wheels being unrestrained apart form the drumand said support means and; power drive means connected to said drum torotate said drum while being cradled between said chains.
 2. Apparatusaccording to claim 1 in which at least some of the support means includemeans for adjusting the effective length of the chain which it supports.3. Apparatus according to claim 1 in which at least some of the supportmeans include resilient means for absorbing tensile forces applied tothe chains.
 4. Apparatus according to claim 3 in which the resilientmeans is rubber.
 5. Apparatus according to claim 1 in which at leastsome of the support means include fluid pressure means for absorbingtensile forces applied to the chains.
 6. Apparatus according to claim 5in which the fluid pressure means is a pneumatic means.
 7. Apparatusaccording to claim 5 in which the fluid pressure means is a hydraulicmeans.
 8. Apparatus according to claim 1 in which each chain is made oflinks, the ends of adjoining links are connected together by an axle,and at least some of the wheels are mounted on such axles, said wheelsbeing adapted so that the drum is rotatably supported by the wheelscontacting the track means to rotate in a direction counter to rotationof the wheels.
 9. Apparatus according to claim 8 in which a substantialnumber of axles support two wheels and the ends of the links joined toan axle are joined thereto between the two wheels.
 10. Apparatusaccording to claim 9 in which the two wheels on the same axle arepositioned to ride on one of the track means mounted on the drum. 11.apparatus according to claim 10 in which the track means is a singlemetal ring mounted on the drum.
 12. Apparatus according to claim 10 inwhich the track means is a pair of metal rings mounted on the drum. 13.Apparatus according to claim 8 in which some links comprise a pair oflink plates and a number of such links have the axle mounted wheelsbetween the link plates.
 14. Apparatus according to claim 1 in whicheach track means is a single metal ring mounted on the drum. 15.Apparatus according to claim 1 in which each track means is a pair ofmetal rings mounted on the drum.
 16. Apparatus compriSing: a pair ofchain with each chain having two ends; the two ends of each chain beingconnected to support means to form a substantially U-shaped loop andwith each loop being spaced from the other loop; at least one end of onechain being adjustable with respect to the support means to vary theheight of the U-shaped chain loop; each chain having a plurality ofwheels rotatably mounted on spaced-apart axles supported by each chain;an essentially horizontally positioned rotatable cylindrical drumcradled in the U-shaped chain loops, with the chains in tension; a pairof spaced-apart circular track means mounted circumferentially on lthedrum with the wheels of each chain being in drum supporting rotatablecontact with a track means; said chain and wheels being unrestrainedexcept by the drum and said support means; and power drive means torotate the drum while being cradled between said chains.
 17. Apparatusaccording to claim 16 in which the axis of the drum is parallel to theaxes of the wheels.
 18. Apparatus according to claim 16 in which theaxes of the wheels are nonparallel to the drum axis.
 19. Apparatusaccording to claim 16 in which the chain is made of links and the linksare maintained out of contact with the drum.
 20. Apparatus according toclaim 16 in which the chains are made of links and the links are joinedtogether with sufficient clearance to permit accommodation ofdimensional variations between the wheels and the drum.
 21. Apparatuscomprising: a horizontally positioned rotatable cylindrical drum; a pairof spaced-apart circular track means mounted circumferentially on thedrum; a pair of spaced-apart nontraveling chains connected to a supportmeans suspending the chains in sling-like contour with said drumsuspended by the chains in cradled arrangement with the chains intension; a plurality of wheels rotatably mounted on spaced-apart axlessupported by each chain, said wheels rotatably contacting one trackmeans and thereby rotatably supporting the drum; the axis of the drumbeing substantially parallel to the axes of the wheels; said chain andwheels being unrestrained except by the drum and said support means; andpower drive means connected to said drum to rotate said drum while beingcradled between said chains.